This invention relates generally to printing apparatus and methods and more particularly to a printing apparatus and method for controlling the printing carriage velocity in an on-the-fly calligraphic printing system.
Mechanical printers have long been available and have increased their printing throughput in order to match the exploding output requirements of today's electronic apparatus. With the advent of both microprocessor controlled devices and the "small computer", the need for fast, reliable, and yet relatively inexpensive printers has resulted in the development and refinement of a number of printing techniques. Among those techniques is the calligraphic printing approach.
In a typical calligraphic printing system, a pen or stylus, together with its drive mechanism, is supported on a moving carriage. The carriage is moved from one writing position to a next writing position. At each writing position the pen or stylus traverses the path of the desired symbol to be written. During the writing time, the carriage is generally at rest.
In order to reduce the time required for printing, apparatus described in copending applications U.S. Ser. Nos. 242,660 and 242,663 employ an "on-the-fly" printing technique wherein the carriage is always moving and the drive mechanism for moving the pen or stylus, carried by the carriage, is dynamically compensated according to the changing position of the carriage. The carriage is generally in motion and carriage acceleration/deceleration time requirements, present when the carriage is stopped at each symbol, are no longer present.
In the particular printer apparatus described in copending U.S. application Ser. Nos. 242,660 and 242,663, the printing carriage which supports the stylus moves along a printing path at a selected velocity while writing is effected on-the-fly. The writing stylus is selectively actuated and positionally controlled to mark a recording medium with intelligible indicia. However, the writing of the various symbols will not, in general, require the same time duration for their completion. This is true even though the spatial extent of or allowed for each character, in the direction of movement of the printing carriage, may be a constant value. Thus, when the carriage velocity is fixed at a constant value, the value is substantially determined by the indicia or symbol which requires the most time to print.
It is therefore an object of this invention to provide, in a calligraphic printing apparatus wherein individual symbols generally require different times for printing, a method and apparatus for increasing average velocity along the printing path without loss in printing quality.
Other objects of the invention are a printing apparatus and method which provide a minimum carriage traverse time for each printing line, the time being generally different from line to line, which are reliable, simple in construction and operation, and which provide increased throughput of operation.